Currently, there is no standard practice among airline companies regarding how to provide the pilot of an aircraft with information about alternate landing destinations, if some reason, such as bad weather or an emergency on board, prevents a landing at the intended destination. An approach taken by some airlines is to provide the pilot with a list of alternate destinations before takeoff or during the flight, via data uplink capabilities, if available. Typically the list includes several "en route" destinations that lie between the point of departure and the intended destination, and several "missed approach" destinations that are located near the intended destination. En route destinations are for use when an emergency, such as a severe illness on board the aircraft, requires a deviation from the intended route prior to arriving at the intended destination. Missed approach destinations are for use when the airplane arrives at the intended destination but is prevented from landing for some reason, such as a stalled aircraft on the runway.
For various reasons, the list of alternate landing destinations provided by an airline is often inadequate to present the pilot with a meaningful choice of where to land the aircraft during an emergency situation, especially if no data uplink is available. First, the alternate landing destinations included on the list are often selected because the airline has support staff located there and not because the destinations are nearby the intended destination. Second, the list, once written, remains unchanged despite conditions that may vary during flight and, therefore, change the desirability of landing at a particular alternate destination. For example, if the aircraft were to encounter a strong head wind that caused an increase in the amount of fuel used, some of the alternate destinations included on the list may be too far to reach safely. Further, because it is impossible to predict where on the route to the intended destination an emergency will occur, the en route list might provide a pilot with an alternate destination that is not the most desirable based on all available alternate destinations because the most desirable alternate destination is not on the list. Finally, the list of alternate destinations does not provide a pilot with dam sufficient for him to make a decision why one alternate landing destination is a better choice than another.
Another approach used by some airlines is to not give the pilot any alternate destination information. If a pilot experiences an emergency en route, he is directed to contact air traffic control to determine the nearest alternate destination. The problem with this approach is that the safety of several hundred passengers is placed in the hands of an air traffic controller being able to think clearly where to direct the aircraft in an emergency situation. Also, this approach does not provide the pilot with any data regarding how long it will take to fly to the alternate destination and how much fuel will be used.
Thus, there exists a need for an alternate destination predictor for aircraft that provides a greatly increased data base of available alternate landing destinations and provides a pilot with sufficient information regarding a deviation from his present route to each of several available alternates so that the pilot can make a better informed decision regarding a route change. The present invention is directed to providing such an alternate destination predictor and, thus, greater autonomy to aircraft containing the predictor.